Power line sag monitoring device

ABSTRACT

The present disclosure relates to systems and methods of sag in a power line. In an embodiment, a monitoring device may include a distance sensor and an operating parameter sensor. A processor of the monitoring device may acquire, via the distance sensor, a first distance measurement. The processor may acquire, via the operating parameter sensor, a first operating parameter measurement. The processor may provide an output signal indicating that the power line is sagging when a combination of the first distance measurement and the first operating parameter measurement exceed a first combined distance-operating parameter threshold.

TECHNICAL FIELD

The present disclosure relates generally to power systems and, moreparticularly, to a device that monitors power line sag.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive embodiments of the disclosure aredescribed, including various embodiments of the disclosure withreference to the figures, in which:

FIG. 1 is a one-line diagram of a power system that includes a powerline with a monitoring system for monitoring power line sag, inaccordance with an embodiment.

FIG. 2 is a side view of the power line of FIG. 1, in accordance with anembodiment.

FIG. 3 is a block diagram of the monitoring system of FIG. 1, inaccordance with an embodiment.

FIG. 4 is a set of plots of thresholds that may be used in processingthe data received by the monitoring system of FIG. 1, in accordance withan embodiment.

FIG. 5 is a logic diagram of processes performed by the monitoringsystem of FIG. 1, in accordance with an embodiment.

FIG. 6 is a plot of thresholds that may be used in processing the datareceived by the monitoring system of FIG. 1, in accordance with anembodiment.

FIG. 7 is another side view of the power line of FIG. 1, in accordancewith an embodiment.

FIG. 8 is a logic diagram of a process performed by the monitoringsystem of FIG. 1, in accordance with an embodiment.

DETAILED DESCRIPTION

One or more specific embodiments will be described below. In an effortto provide a concise description of these embodiments, not all featuresof an actual implementation are described in the specification. Itshould be appreciated that in the development of any such actualimplementation, as in any engineering or design project, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but would nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

Power lines are commonly used to deliver power from a power generator toone or more loads. Such power lines may include one or more conductorsto conduct energy between the power generator and the loads and areoften installed on overhead structures or buried underground. Forexample, a power lines may be suspended between overhead structures toprevent the power line from discharging power onto the ground, anotherpower line, or another object. Ambient temperature, wind speed,humidity, and other environmental factors may affect the power linetemperature. Further, the amount of energy delivered on the power linemay also affect the power line temperature.

As the power line temperature increases, the power line may expandcausing the power line to sag a certain amount towards the ground. Sagmay refer to a distance to which the power line sinks towards the groundor other objects due to slack in the power line between overheadstructures. Slack may refer to additional conductor length betweenoverhead structures than if the conductor were taut (e.g., tightlycoupled) between the overhead structures. As used herein, sagging mayrefer to a power line that has more slack between overhead structuresthan a desired (e.g., reference) amount of slack. The amount of sag maycause the power line to approach or to contact other objects, such asvegetation, which may lead to power losses or may violate local codes.Accordingly, there is a need for improved methods of determining the sagof a power line.

Systems and methods described below may monitor a power line by using acombination of sensors to more reliably determine sag and otherproperties of the power line than using data from a single sensor. Amonitoring device may monitor various operating parameters of the powerline, such as distance from the power line to the ground, ambienttemperature of the surrounding environment of the power line, andcurrent of the power line. For example, the monitoring device mayprovide an alarm when a combination of two or more measurements fromoperating parameters exceed a combined threshold that is based on eachof the two or more operating parameters. For instance, the monitoringdevice may provide an output signal indicating that the power line issagging when a combination of distance and temperature measurementsexceed a threshold. In some embodiments, the monitoring device maydetermine a change in one or more operating parameters over time, suchas change distance over time, change in temperature over time, or changein current over time, to monitor the physical properties of the powerline. Moreover, in certain embodiments, the monitoring device maymonitor both line sag and discharge events on the power line. In suchembodiments, the monitoring device may measure tilt of the power line toestimate the sag. By monitoring angular changes in tilt, the monitoringdevice may be positioned on the power line closer to a structure thatsupports the power line to allow the monitoring device to more reliablydetect discharge events that occur at or proximate to the structure. Themonitoring device may provide an alarm when the sag on the power lineexceeds a threshold.

FIG. 1 illustrates a one-line diagram of a power delivery system 20having a power generator 22 electrically coupled to one or more loads 24via a power line 26. The power delivery system 20 may be, for example, athree-phase power delivery system. The power line 26 may include amonitoring device 30, such as a line mounted, line powered (LMLP)device. The monitoring device 30 may monitor the power line 26 viasensors 32 to detect various operating parameters of the power line 26,such as ambient temperature, wind speed, humidity, current, voltage,distance to the ground, acceleration, sound, light, and the like. In theillustrated embodiment, the monitoring device 30 may determine sag ofthe power line 26 based on the one or more operating parameters of thepower line 26 detected via the sensors 32. The monitoring device 30 mayinclude a transceiver 40 that communicates with one or more otherintelligent electronic devices (IEDs) (e.g., central IED 36, substationIED 37 at a substation 34, etc.) and/or a central monitoring station 38via the transceivers 42, 43, and 44.

The monitoring device 30 may communicate data over a wide-areacommunications network of electronic devices or may communicate directlywith the IEDs 36 and 37 and/or the central monitoring station 38. In theillustrated embodiment, the substation relay 37 may include a currenttransformer 46 and a circuit breaker 48 to monitor and controlelectrical characteristics of the power line 26. According to variousembodiments, central monitoring system 38 may comprise one or more of avariety of types of systems. For example, central monitoring system 38may include a supervisory control and data acquisition (SCADA) systemand/or a wide area control and situational awareness (WACSA) system.

A communication network between the monitoring device 30, the IEDs 36and 37, and the central monitoring station 38 may be facilitated bynetworking devices including, but not limited to, multiplexers, routers,hubs, gateways, firewalls, and switches. In some embodiments, IEDs andnetwork devices may comprise physically distinct devices. In otherembodiments, IEDs and network devices may be composite devices, or maybe configured in a variety of ways to perform overlapping functions.IEDs and network devices may comprise multi-function hardware (e.g.,processors, computer-readable storage media, communications interfaces,etc.) that can be used in order to perform a variety of tasks thatpertain to network communications and/or to operation of equipmentwithin the power delivery system 20.

FIG. 2 is a side view of the power line 26, in accordance with anembodiment. In the illustrated embodiment, a segment 50 of the powerline 26 is suspended overhead between a first structure 52 and a secondstructure 54. The power line 26 may include jumpers 56 and 58 toelectrically couple the segment 50 to one or more other segments of thepower line 26. In some embodiments, the monitoring device 30 maymonitor, for example, one or more of the phases of multi-phase powersystem (e.g., two phase, three phase, six phase). In the illustratedembodiment, the sag 60 may refer to the difference between the height 62at which the segment 50 of the power line 26 is suspended and the height64 at which the segment 50 sinks towards the earth. The monitoringdevice 30 may be positioned at a midpoint of the segment 50 of the powerline 26 where the sag of the power line 26 is likely to be the largest.In some embodiments, sag may be estimated based on angular changes,referred to as tilt, in the power line 26 to allow the monitoring device30 to be positioned toward an end of the segment 50 of the power line26.

Conventional sag detection systems may determine a distance based on asingle measurement. For example, some sag detection systems may measurethe distance to the nearest object. However, these systems may beunreliable due to using a single measurement to analyze sag. Forexample, the nearest object may be an animal which may cause a change inthe distance measurement, thereby causing sag to be overestimated.Further, because distance is likely to be the largest at the midpoint ofthe power line 26, some systems may be positioned at the midpoint todetect the shortest distance. Because these systems are positioned atthe midpoint, it may be more difficult to determine other desirableinformation regarding the power line 26.

As explained below, the monitoring device 30 may include various sensors32 to monitor various operating parameters of the power line, such asdistance from the power line 26 to an object or ground, ambienttemperature of air surrounding the power line 26, current of the powerline 26, wind speed near the power line 26, movement of the power line26, or any combination thereof. As heat of the power line 26 increases,the sag of the power line 26 may increase. In some embodiments, by usinga combination of measurements (e.g., a combination of distance andcurrent, a combination of distance and ambient temperature, etc.),alarms regarding sag may be more reliably provided than when using asingle measurement. Additionally and/or alternatively, by measuringchanges to such operating parameters over time, the resulting alarms maybe more reliable than alarms resulting from a single measurementcompared to a threshold. Moreover, in some embodiments, the monitoringdevice 30 may be positioned at a location other than the midpoint. Forexample, angular tilt of the line may be used to determine the sag ofthe power line 26. By monitoring the power line 26 at a location closerto a structure, the monitoring device 30 may more reliably determine,for example, whether a discharge event has occurred at or near thestructure.

FIG. 3 is a block diagram of the monitoring device 30 used to determinesag of the power line 26, in accordance with an embodiment. In theillustrated embodiment, the monitoring device 30 is operably coupled tosensors 32. As used herein, the monitoring device 30 may refer to anymicroprocessor-based device that monitors and/or protects monitoredequipment within the electric power delivery system 20, such as an IED.Such devices may include, for example, programmable logic controllers(PLCs), programmable automation controllers, input and output modules,digital relays, and the like. The term IED may be used to describe anindividual IED or a system comprising multiple IEDs.

In the illustrated embodiment, the monitoring device 30 includes a bus80 operably coupling a processor 82 or processing unit(s) to a memory84, a computer-readable storage medium 86, input circuitry 88, andcommunication circuitry 89. The computer-readable storage medium 86 mayinclude or interface with software, hardware, or firmware modules forimplementing various portions of the systems and methods describedherein. The tangible, non-transitory computer-readable storage medium 86may be the repository of one or more modules and/or executableinstructions configured to implement any of the processes describedherein.

The processor 82 may be configured to process inputs received via theinput circuitry 88. In the monitoring device of FIG. 3, the processor(s)82 may be operably coupled with the memory 84 and the nonvolatilestorage 86 to perform various algorithms described herein. Such programsor instructions executed by the processor(s) 82 may be stored in anysuitable article of manufacture that includes one or more tangible,computer-readable media at least collectively storing the instructionsor routines, such as the memory 84 and/or the nonvolatile storage 86.The memory 84 and the nonvolatile storage 86 may include suitablearticles of manufacture for storing data and executable instructions,such as random-access memory, read-only memory, rewritable flash memory,hard drives, and optical discs. These computer program instructions maybe provided to a processor of a general-purpose computer, specialpurpose computer, or other programmable data processing apparatus toproduce a machine, such that the instructions, which executed via theprocessor of the computer or other programmable data processingapparatus, causes the processor to implement the operations describedwith respect to FIGS. 4-8. In some embodiments, the processor 82 and/orthe computer-readable storage medium 86 and the modules therein may beembodied as a microprocessor, a general purpose integrated circuit, aField Programmable Gate Array (“FPGA”), one or more Application SpecificIntegrated Circuits (“ASICs”), and/or other programmable logic devices.

While the monitoring device 30 is used to perform the processingdescribed herein, some or all of the processes described herein may beperformed at the one or more other IEDs (e.g., the central IED 36 and/orthe substation IED 37) and/or the central monitoring station 38. Forexample, the IED 30 may communicate the data (e.g., electrical data,radio data, ultrasonic data, temperature data, acceleration data, tiltdata, etc.) to the substation IED 37 to cause the substation IED 37 toperform the processes described herein and to control operation of thecircuitry breaker 48 based on the processes. For instance, if thesubstation IED 37 determines that an event (e.g., acceleration event,sagging event, etc.) has occurred based on measurements from the IED 30,the substation IED 37 may electrically disconnect loads 24 via thecircuit breaker 48.

In the illustrated embodiment, the input circuitry 88 receiveselectrical signal(s) from various operating parameter sensor(s), such asan electrical sensor 32, a radio frequency (RF) antenna 98, an acousticsensor 100, an ultrasonic sensor 102, a temperature sensor 110,accelerometer, tilt sensor, current sensor, and the like. For example,the input circuitry 88 may receive electrical signal(s) from theelectrical sensor 32 to detect one or more electrical characteristics ofthe power being delivered on the power line 26. For instance, the inputcircuitry 88 may receive a current signal from the current transformer94. The input circuitry 88 may include a potential transformer 120 thattransforms the current signal to a level that may be sampled.

Further, the input circuitry 88 may receive an RF signal from the RFantenna 98 and an audio signal from an acoustic sensor 100. The RFantenna 98 may be any suitable antenna to detect radio wave(s). The RFantenna 98 may convert energy from the detected radio wave into a radiosignal to allow the monitoring device 30 to monitor the radio wavesemitted due to electromagnetic waves caused by discharge events. The RFantenna 98 may be operatively coupled to any suitable input circuitry88, such as encode/decode circuitry, to enable the processor 82 to usethe received radio signals.

Similarly, the acoustic sensor 100 may be any suitable sensor thatdetects sound wave(s), such as a microphone, a pressure transducer, orthe like. The acoustic sensor 100 may convert energy from the soundwaves into an audio signal to monitor the sound waves received by theacoustic sensor 100. The acoustic sensor 100 may be operatively coupledto any suitable input circuitry 88, such as capacitors, amplifiers, orthe like, to allow the processor 82 to use the received audio signals.

In the illustrated embodiment, the input circuitry 88 receives a signalindicative of a distance measurement from a distance sensor, such as anultrasonic sensor 102, a light detection and ranging (LIDAR) sensor,radio detection and ranging (RADAR), or the like. For example, theultrasonic sensor 102 may direct ultrasonic sound waves 122 towardsground. Some or all of the ultrasonic sound waves 122 may be reflected124 back to the ultrasonic sensor 102. A distance to a nearest object orground may be measured based on the difference in time between when theultrasonic sound wave 122 is transmitted and when the reflected waves124 are received. The ultrasonic sensor 102 may provide distancesignal(s) indicating distance measurements to the ground or the nearestobject based on a difference in time between transmitting the ultrasonicsound wave 122 receiving the reflected wave 124.

Additionally and/or alternatively, the input circuitry 88 may receive asignal indicative of an acceleration measurement of the monitoringdevice 30 from an accelerometer 108. The accelerometer 108 may be anysuitable accelerometer that detects acceleration of the power line 26and is further described in conjunction with FIG. 8.

The input circuitry 88 may receive, from the temperature sensor 110, atemperature signal indicative of ambient temperature of air surroundingthe power line 26. In the illustrated embodiment, the temperature sensor110 may provide an analog signal to the A/D converter(s) 112 indicativeof the ambient temperature.

A/D converter(s) 112 may sample each of the signals from the potentialtransformers 120 and 122, the RF antenna 98, the acoustic sensor 100,the ultrasonic sensor 102, and/or the temperature sensor 110. The A/Dconverter(s) 112 may produce digitized analog signals representative ofmeasured current, measured voltage, measured sound waves, measured radiowaves, measured acceleration, and measured temperature. The measurementsmay be in a digital format or other format. In certain embodiments, theinput circuitry 88 may be used to monitor current signals associatedwith a portion of an electric power delivery system.

The A/D converter 112 may be connected to the processor 82 by way of thebus 80, through which digitized representations of current signal, thevoltage signal, the RF signal, the audio signal, the distance signal,and the acceleration signal may be transmitted to the processor 82.Depending on the implementation, the any of the sensors may providedigital and/or analog signals to the input circuitry 88. In someembodiments, digital signals from the sensors may be provided directlyto the bus 80. As described above, the processor 82 may be used tomonitor and protect portions of the electric power delivery system 20,and issue control instructions in response to the same (e.g.,instructions implementing protective actions).

In the illustrated embodiment, the input circuitry 88 may providedigital signals representative of the current measurements, the RFmeasurements, the audio measurements, the temperature measurements, thedistance measurements, and the acceleration measurements, to theprocessor 82 via the bus 80. The processor 82 may receive the digitalsignals representative of the current signal from the currenttransformer 94, the radio signal from the antenna 98, the audio signalfrom the acoustic sensor 100, the distance signal from the ultrasonicsensor 102, the acceleration signal from the accelerometer 108, and thetilt signal from the tilt sensor 109. The processor 82 may determine sagof the power line 26 based on the digital representations of one or moreof the signals. For example, the processor 82 may determine sag based onthe current measurements, the distance measurements, the temperaturemeasurements, and/or tilt measurements, among others.

The processor 82 may provide an output signal indicating the sag viacommunication circuitry 89 of the monitoring device 30, such as thetransceiver 40 and/or one or more alarms 90. For example, the processor82 may send the output signal to the IED 36 and/or the centralmonitoring station 38 to allow the central monitoring station 38 todisplay an amount of sag on a display at the central monitoring station38. This may allow an operator to further inspect the power line 26. Insome embodiments, the processor 82 may send an output signal indicatingthe sag of the power line 26 to the IED 36 and/or the central monitoringstation 38 to cause the IED 36 or another IED to perform a protectiveaction on the power delivery system 20. For example, the processor 82may send the output signal indicating that the power line 26 is saggingto cause the IED to open a circuit breaker to disconnect the power line26 from the power delivery system 20. While two antennas 40 and 98 areshown, this is meant to be illustrative and, in some embodiments, thesame antenna may be used for communication as well as monitoring thepower line 26 for radio waves.

In some embodiments, the communication circuitry 89 may include one ormore alarms 90, such as light emitting diodes (LEDs), displays, audiblesounds, or the like, to notify an operator of the sag of the power line26. For example, the processor 82 may send an output signal to controloperation of one or more of the alarms 90 to provide an indication, forexample, that sag has increased beyond a desired amount if one or morethresholds are exceeded.

FIG. 4 is a set of plots 140 and 142 illustrative of a combination ofsensor data regarding sag of the power line 26. While the plots 140 and142 are depicted visually for explanatory purposes, in some embodiments,the processor 82 may execute instructions stored on the memory andperform the operations described herein without generating a visualplot. Note that, while current, distance, and temperature are used asexamples of operating parameters being monitored in combination with oneanother, any suitable combination of two or more operating parametersmay be used. The thresholds described below may depend upon theimplementation. In some embodiments, the thresholds may be user inputsreceived, via the communication circuitry 89 or other input structures,and stored in the memory 84.

The plot 140 illustrates an operating parameter, such as current (I(A)),on a first axis 144, with distance to the ground or nearest object(D(m)), on a second axis 146. The processor 82 may determine,independent of distance, whether the current measurements exceed acurrent threshold associated with an overcurrent condition of the powerline 26. If the current threshold 150 is exceeded, the processor 82 mayprovide an output signal indicating that current on the power line 26 isexceeding the overcurrent condition. Similarly, the processor 82 maydetermine, independent of current, whether the distance of the powerline 26 to the ground or nearest object falls below a distance threshold152. If the distance falls below the distance threshold 152, an outputsignal may be provided indicating that the power line is sagging. Forexample, the distance threshold 152 may be a threshold associated withthe height 64 of the power line 26.

Further, the processor 82 may determine whether a combination of thecurrent measurements and the distance measurements exceeds a firstcombined current-distance threshold 156 (e.g., falls outside of a normaloperation region) and provide the output signal indicating that thefirst combined threshold is exceeded. That is, the first combinedcurrent-distance threshold 156 may be a threshold that indicates that agreater current than desired is being provided via the power line 26 incombination while the power line 26 sinking toward the ground more thandesired. The processor 82 may provide an output signal indicating thatthat the first combined current-distance threshold is exceeded (e.g.,operating outside of the normal operation region). For example, theprocessor 82 may send the output signal to an IED to cause the IED toopen a circuit breaker to reduce current being delivered on the powerline 26 to limit the power being delivered on the power line 26 to bewithin the normal operating region. As such, the processor 82 may sendthe output signal to cause an IED to limit the combination of distanceand current of the power line 26 to not exceed desired levels.

In some embodiments, the processor 82 may provide an output signalindicating that additional current and/or distance is available on thepower line 26 when the combination of current and distance is below asecond combined current-distance threshold 158. That is, if thecombination of current and distance falls below the second thresholdcurrent-distance threshold 158, the power line 26 may be allowed to sagmore by increasing energy transferred on the power line 26 withoutcausing excess sag (e.g., operating in the normal operating region). Assuch, the processor 82 may provide an output signal indicating thatadditional bandwidth is available on the power line 26 to allow foradditional loads to be powered by the electrical power delivery system20.

The plot 142 illustrates another operating parameter, such astemperature, on a first axis 160 and distance on an ordinate axis 162.The processor 82 may determine, independent of distance, whether ambienttemperature measurements exceed a temperature threshold 170. If thetemperature threshold 170 is exceeded, an output signal may be providedindicating that the power line 26 has exceeded an overtemperaturethreshold. Similarly, if the distance from the monitoring device 30 tothe ground or nearest object falls below the distance threshold 152, anoutput signal may be provided independent of the temperature, asdescribed above.

The processor 82 may determine whether a combination of temperature anddistance exceeds a first combined temperature-distance threshold 172. Inthe illustrated embodiment, the processor 82 provides an output signalindicating that the temperature and distance of the power line exceedsthe first combined temperature-distance threshold 172 (e.g., operatesoutside of a desired normal operation region). For example, theprocessor 82 may send the output signal to an IED to cause the IED toopen a circuit breaker to reduce current being delivered on the powerline 26 to reduce the ambient temperatures surrounding the power line tocause the power line to operate within the normal operating region. Assuch, the processor 82 may send the output signal to cause an IED tolimit the combination of distance and temperature of the power line 26to not exceed desired levels.

If the combination of temperature and distance is below a secondcombined temperature-distance threshold 174, additional energy may betransferred on the power line 26 without causing excess sag. As such,the processor 82 may provide an output signal indicating that additionalbandwidth is available on the power line 26 when the temperature anddistance fall below the combined temperature-distance threshold 174.Additionally and/or alternatively to the combined monitoring of variousoperating parameters, the monitoring device 30 may monitor changes inoperating parameters over time.

FIG. 5 is a logic diagram of a process performed by the monitoringdevice 30 to monitor changes in operating parameters, such as current,temperature, and/or distance, over time. One or more operatingparameters may be compared to operating parameter over-time thresholdsto determine whether a condition is persisting on a power line 26. Bymonitoring the operating parameters over time, conditions that causeincreased wear and tear on the power line 26 may be limited which maynot be detected if the power line 26 were monitoring with other methods(e.g., current compared to over current thresholds for fault detection).

The processor 82 may receive the digital representation of currentmeasurements 202 of the power line 26. The processor 82 may determinewhether the current measurements from a first time to a second timepersist to exceed a current-over-time threshold. The first time andsecond time may be over various periods of time (e.g., milliseconds,seconds, minutes, hours, etc.) to prevent heating of the power line 26from exceeding the physical properties that the power line 26 wasdesigned to withstand. The processor 82 may provide an output signal 206indicating the overcurrent event if the current on the power line 26 haspersisted over a period of time to be greater than the desired amount.By monitoring current over time, as described with FIG. 4, the processor82 may more reliably detect greater current being delivered on the powerline 26 than desired amounts and provide output signals of such events.As such, the monitoring device 30 may notify operators of such events toallow for reduced annealing caused by overheating of the power line 26.By protecting the power line 26 from annealing, the conductors of thepower line 26 may maintain the desired strength and last for a greaterduration than in systems that monitor current without monitoring howlong such currents persist.

Similarly, the processor 82 may receive the digital representation oftemperature measurements 212 indicative of ambient temperatures of thepower line 26. The processor 82 may compare the temperature over time toone or more temperature-over-time thresholds. If ambient temperaturespersist over time 214 to exceeds the temperature-over-time threshold,the processor 82 may provide an output signal 216 indicative of thetemperature-over-time event. Similar to the above example, by monitoringambient temperatures of the power line 26 over time, the processor 82may more reliably detect greater amounts of heat surrounding the powerline 26 that persist which may cause annealing. By protecting the powerline 26 from such temperature-over-time events, the conductors of thepower line 26 may maintain the desired strength and last for a greaterduration than in systems that monitor ambient temperatures withoutmonitoring how long such temperatures persist.

Likewise, the processor 82 may receive the digital representation ofdistance measurements 222 indicative of the distance from the ultrasonicsensor 102 to the ground or nearest object. The processor 82 may comparedistance measurements over time to a distance-over-time threshold 154.If the distance over time 214 persists to exceeds a distance-over-timethreshold, the processor 82 may provide the output signal 226 indicatingthat the power line 26 is sagging. By monitoring the distance over time,short variations in the distance, for example, caused by moving objects,may be avoided to enable more reliable monitoring of the sag of thepower line 26. Further, at OR 228, the processor 82 may provide anoutput signal if any combination of alarms indicates that an over-timethreshold has been exceeded.

In some embodiments, the change in distance of the power line 26 may bemonitored via an accelerometer. That is, the processor 82 may determinethe acceleration (d²D/dt²) of the power line. The processor 82 mayfurther determine wind speed, ice shedding, or both, based onacceleration of the monitoring device 30 detected by the accelerometer.

FIG. 6 is a plot of changes in distance over time (dD/dt) with respectto distance. Note that, while changes in distance over time with respectto distance are used in the illustrated embodiment, similar analysis maybe performed using changes in temperatures over time with respect totemperature, changes in current over time with respect to current, orany other suitable operating parameter of the power line 26. The plot240 includes distance from the ground or nearest object in meters on afirst axis 242 and a change in distance with respect to time on a secondaxis 244. As mentioned above, the processor 82 may determine whether thedistance exceeds distance threshold 152. Further, the processor 82 maydetermine whether the distance and the distance over time dD/dt exceedsa combined distance dD/dt threshold 250. If the measured distance andthe measured distance over time exceeds the combined threshold 250, theprocessor 82 may provide the output signal indicating that the powerline 26 is sagging or likely to begin sagging.

The monitoring device 30 may be used to monitor a variety of operatingparameters associated with the power line 26. For example, themonitoring device 30 may be used to monitor and detect faults on thepower line 26 based on current measurements of the power line 26. Asanother example, the monitoring device 30 may be used to detectdischarge events associated with operation of the power line 26.Discharge events may refer to partial discharge and/or corona dischargeof the power line 26. For example, due to aging, insulation between thestructure 52 and the power line 26 may degrade. Due to this degradation,energy may be discharged from the power line 26 to ground or anotherconductor through the degraded insulation, resulting in power losses inthe power delivery system 20. Sound waves, RF waves, and/or travelingwaves may be emitted due to these discharge events.

FIG. 7 is another example of the monitoring device 30 that may be usedto determine sag and to detect discharge events of the power line 26.The monitoring device 30 may be positioned on the power line 26 at alocation other than a midpoint of the power line. That is, themonitoring device 30 may be mounted to the power line 26 to a positionproximate to a structure. In some embodiments, the monitoring device 30may be positioned closer in proximity to the first structure 52 of thepower line 26 than to a midpoint of the span between the first structure52 and the second structure 54 to allow the monitoring device 30 to moreaccurately detect discharge events while determining sag in the powerline 26. For instance, the monitoring device 30 may be positionedproximate to the first structure 52 to allow the monitoring device 30 todetect sound waves, RF waves, and/or traveling waves emitted from adischarge event at the insulation of the first structure 52. That is,sensor circuitry, such as the current transformer 94, the antenna 98 andthe microphone 100, may be coupled or positioned proximate to the powerline 26 such that the sensor circuitry is closer to the first structure52 than a midpoint between the first structure 52 and the secondstructure 54. In some embodiments, the monitoring device 30 may bemounted on the first structure 52 or adjacent to the first structure 52.

Because the monitoring device 30 is positioned at a location other thanthe midpoint, sag of the power line 26 may be inferred without directmeasurement of the distance. The monitoring device 30 may determine thesag of the power line 26 at the midpoint by inferring from tilt anglesreceived from the tilt sensor 109 positioned proximate to the structure52. For example, the processor 82 may infer the sag via a look-up tableof tilt angles to approximate the sag at the midpoint.

By positioning the monitoring device 30 in a position other than themidpoint between the first structure 52 and the second structure 54, themonitoring device 30 may provide additional information regardingdischarge events. For example, the processor 82 may provide a firstoutput signal when the tilt angle measurements indicate that the powerline is sagging based on the inferred sag from tilting of the power line26, and the processor 82 may provide a second output signal when the oneor more operating parameter measurements, such as the measurements ofthe RF signal, the audio signal, or the like, indicate that a dischargeevent has occurred. The first output signal and/or the second outputsignal may be received at the monitoring station to be displayed on adisplay at the monitoring station to notify an operator if the powerline is sagging and/or a discharge event has occurred. In someembodiments, the monitoring device 30 may notify the monitoring stationof the type of indication (e.g., a sag indication, current-over-timeindication, etc.) as well as provide the corresponding measurements.

In some embodiments, wind speed, and/or ice shedding, among others, maybe determined by inferring, from acceleration measurements, aspects ofthe power line 26. The monitoring device 30 may detect these events ofthe power line 26 based on the acceleration of the accelerometer of themonitoring device 30.

FIG. 8 is a logic diagram of a process 300 performed by the processor 82to detect an acceleration event of the power line. Further, FIG. 8includes a 3D coordinate system 302 that illustrates an x-axis 304, ay-axis 306, and a z axis 308 that may be used in conjunction with theflow diagram. The processor 82 may determine whether a combination ofacceleration, speed, and distance of movement in the x direction (block310) exceed an x-direction threshold 312 via comparator 314. Further,the processor 82 may determine whether a combination of acceleration,speed, and distance of movement in they direction (block 318) exceed ay-direction threshold 320 via comparator 322. Likewise, the processor 82may determine whether a combination of acceleration, speed, and distanceof movement in the z-direction (block 324) exceed a z-directionthreshold 326 at comparator 328. Based on whether any of the thresholdsare exceeded, the processor 82 may provide an output signal indicatingthe movement and/or location of the power line 26.

To detect an acceleration event of the power line, the processor 82 maydetermine whether any combination of movement of the monitoring device30 exceeds the x-direction threshold 312, y-direction threshold 320, andz-direction threshold 326 at OR 330. The processor 82 may provide anoutput signal indicating that the power line 26 is moving greater thanat least one of the x-direction threshold 312, the y-direction threshold320, and the z-direction threshold 326. For example, the processor 82may send the output signal to a display of the monitoring device 30 toindicate that the acceleration event has occurred. In other embodiments,the processor 82 may communicate the output signal to another electronicdevice via the communication circuitry 89 to allow an operator to assessthe acceleration event.

The specific embodiments described above have been shown by way ofexample, and it should be understood that these embodiments may besusceptible to various modifications and alternative forms. It should befurther understood that the claims are not intended to be limited to theparticular forms disclosed, but rather to cover all modifications,equivalents, and alternatives falling within the spirit and scope ofthis disclosure.

The techniques presented and claimed herein are referenced and appliedto material objects and concrete examples of a practical nature thatdemonstrably improve the present technical field and, as such, are notabstract, intangible or purely theoretical. Further, if any claimsappended to the end of this specification contain one or more elementsdesignated as “means for [perform]ing [a function] . . . ” or “step for[perform]ing [a function] . . . ”, it is intended that such elements areto be interpreted under 35 U.S.C. 112(f). However, for any claimscontaining elements designated in any other manner, it is intended thatsuch elements are not to be interpreted under 35 U.S.C. 112(f).

What is claimed is:
 1. A monitoring device configured to monitor a powerline, comprising: a distance sensor configured to measure a distancefrom the power line to ground; an operating parameter sensor configuredto measure an operating parameter of the power line; a memory; aprocessor operatively coupled to the memory, wherein the processor isconfigured to: acquire, via the distance sensor, a first distancemeasurement; acquire, via the operating parameter sensor, a firstoperating parameter measurement; provide a first output signal when acombination of the first distance measurement and the first operatingparameter measurement falls outside of a normal operating region.
 2. Themonitoring device of claim 1, wherein the processor is configured toprovide the first output signal when the first distance measurementfalls below a distance threshold, independent of the first operatingparameter measurement.
 3. The monitoring device of claim 1, wherein theoperating parameter comprises at least one of current of the power lineand temperature of power line.
 4. The monitoring device of claim 1,wherein the processor is configured to provide the first output signalwhen the first operating parameter measurement exceeds an operatingparameter threshold, independent of the distance.
 5. The monitoringdevice of claim 1, wherein the processor is configured to provide thefirst output indicating that the combination of the first distancemeasurement and the first operating parameter exceed a first combineddistance operating parameter threshold, and to provide a second outputsignal indicating that additional bandwidth is available when acombination of the first distance measurement and the first operatingparameter measurement fall below a second combined distance-operatingparameter threshold.
 6. The monitoring device of claim 1, wherein theprocessor is configured to: determine a change in the distance betweenthe first distance measurement measured at a first time and a seconddistance measurement measured at a second time; and provide an alarmwhen a combination of the first distance measurement and the change inthe distance between the first time to the second time exceeds acombined distance dD/dt threshold.
 7. The monitoring device of claim 1,wherein the processor is configured to detect a fault on the power linebased on the operating parameter.